The auditory and tactile systems convert mechanical energy into neural activity for the purposes of perceiving our environment. This commonality suggests that the two sensory systems may use similar mechanisms for encoding stimulus intensity, but the manner in which this occurs is still unresolved for both systems. Furthermore, although there are many similarities between these two systems, their peripheral organization is quite different. The experiments proposed in this subproject are designed to determine the basic physiology of certain aspects of the tactile system and to compare and contrast the organizing principles found in audition and taction. The studies are designed to determine if differences in peripheral nerve activity result in different protocols for intensity coding between the two systems, or if the systems are essentially similar despite the peripheral diversity. Another goal is to determine the mechanisms involved in tactile intensity coding, relating these to the tactile psychophysical phenomenon and morphological substrates. Thus one long-range goal is to understand how tactile receptors encode stimulus intensity and how the peripheral nerve fibers convey the information to central-nervous-system location. using the cat as the animal model for humans, we will determine the peripheral physiology in response to sinusoidal and complex stimuli and like the response properties to their anatomical endorgans. Furthermore, we will test the hypothesis the loci of transduction in tactile receptors are elements (filopodia) that project from the nerve fibers that innervate the various endorgans. We will do this using well-established physiological recording methods and electron microscopy. Lastly, enzymatic and mechanical removal of the Pacinian corpuscle's accessory capusle and attendant electrophysiology should reveal basic mechanisms of transductions of importance both for audition and taction. The results will provide scientific rational for methods that can be used to devise treatments and prosthetic devices, to ameliorate partial or profound deafenss, and to recruit the use of the tactile system as a surrogate input for auditory information.